The Photoshop Alphabet

A - Path Selection Tool/Direct Selection Tool. (aka the Arrow tool)
B - Brush
C - Crop
D - Default Foreground and Background Colors (black foreground/white background)
E - Eraser
F - Full screen mode
G - Gradient/Paint Bucket
H - Hand (or, press and hold "space")
I - Eyedropper Tool (I = "eye")
J - Healing Brush Tool (and others) (no mnemonic)
K - Knife tool (don't let the silent K fool you!)
L - Lasso Tool(s)
M - Marquee Tool
N - Notes Tool
O - Dodge Tool (and Burn and Sponge)
P - Pen Tool
Q - Quick Mask mode
R - Blur Tool (and Sharpen and Smudge)
S - Clone Stamp Tool (and Pattern Stamp Tool)
T - Type Tool
U - Line Tool (and other shapes) (no mnemonic)
V - Move Tool
W - Magic Wand
X - Swap foreground and background colors (you can see how X is kind of like "switch")
Y - History Brush Tools (no mnemonic)
Z - Zoom Tool (or, press and hold command/control-space to zoom in and option/alt-command/control-space to zoom out)